20685287 has 4 divisors (see below), whose sum is σ = 23640336. Its totient is φ = 17730240.

The previous prime is 20685239. The next prime is 20685307. The reversal of 20685287 is 78258602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20685287 - 2¹⁰ = 20684263 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20685287.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20685227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1477514 + ... + 1477527.

It is an arithmetic number, because the mean of its divisors is an integer number (5910084).

Almost surely, 2^20685287 is an apocalyptic number.

20685287 is a deficient number, since it is larger than the sum of its proper divisors (2955049).

20685287 is an equidigital number, since it uses as much as digits as its factorization.

20685287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2955048.

The product of its (nonzero) digits is 53760, while the sum is 38.

The square root of 20685287 is about 4548.1080681971. The cubic root of 20685287 is about 274.5072697457.

The spelling of 20685287 in words is "twenty million, six hundred eighty-five thousand, two hundred eighty-seven".